The Los Angeles Times reports that when money's tight, many people switch to cheap, unhealthful processed foods. Karen Ravn writes,

Prices are way down on the stock market and way up at the grocery store. Just thinking about it could make you lose your appetite -- or, alternatively, give you a serious craving for some comfort food. Indeed, as the economy flags, sags and drags, there's talk that it could affect the way people eat, and even how much they weigh.

You might imagine that high food prices could put the nation on a diet as people, strapped for cash, tighten their belts and eat less. Forget that idea. Many nutrition experts fear that soaring food prices will have the opposite effect -- fatten up the nation.

They point to science showing that price changes can make people change what they buy as well as how much. As the price of one food goes up, people not only buy less of it, but they also sometimes buy other, cheaper food in its place. And cheaper foods tend to have more calories than those with a higher price tag. For instance, as the price of oranges goes up, people don't buy as many oranges. And some may decide to buy cookies instead. Today, "people are eating cheap, unhealthy food who never thought they would be," says Adam Drewnowski, director of the Center for Obesity Research at the University of Washington in Seattle.

It's no accident that high-calorie foods (chips, dips, cookies, candy) are generally cheaper than low-calorie foods (broccoli, asparagus, peaches, blueberries). Processed foods are cheaper to produce, ship and store. As researchers note, this is partly due to agricultural policies, which could be changed, and partly due to the nature of the foods themselves, which can't.

"You can see how this situation could fuel both under-nutrition and over-nutrition," says Kelly Brownell, director of the Rudd Center for Food Policy and Obesity at Yale University in New Haven, Conn.

But despite the fact that a diet could easily get derailed during these lean economic times, it doesn't have to be that way. In a related story, we provide some simple tips to help you stay on track and eat cheaply -- and healthfully.

Price of eating right

Drewnowski has been arguing for years that healthful eating isn't just a matter of choosing the right foods. It's also a matter of being able to afford those choices. "Simply put," he writes for an upcoming publication of the University of Washington's School of Public Health, "fats and sweets cost less, whereas healthier diets cost more."

He has data to back that up. In a 2004 paper published in Nutrition Today, he and co-author Anne Barratt-Fornell, a cancer and health information consultant at the University of Michigan Comprehensive Cancer Center Ann Arbor, assessed 200 foods being sold in a Seattle supermarket and found that, in general, the more "energy dense" a food is -- i.e. the more calories it contains per unit weight -- the less it costs per calorie. In other words, customers got more caloric bang for their buck if they bought foods full of fat, sugar and starch than if they bought foods full of vitamins, minerals and fiber.

At 2003 retail prices, shoppers could have bought all the calories they needed to get through a day for less than $1 if they bought them solely in the form of refined grains, added sugars and added fats. At the other extreme, a day's worth of calories would have cost several hundred times more if buyers got them all from fresh salmon, arugula and raspberries. (The sugar in fresh raspberries, for instance, costs about 100 times as much as the plain old refined sugar that comes in a bag.)

The price difference between low- and high-calorie foods seems to be growing, according to a 2007 study in the Journal of the American Dietetic Assn. by Drewnowski and Pablo Monsivais, a research analyst at the Center for Public Health Nutrition at the University of Washington. Using retail figures from major supermarket chains in the Seattle area, the researchers compared the prices of 372 foods and beverages in 2004 and 2006.

The average price increase was 7.9%. But the increase was not uniform. After dividing all the solid foods into five levels -- from highest in calories per gram to lowest -- the researchers found that prices of the foods most dense in calories had actually dropped slightly, by an average of 1.8%. But prices of the lowest-calorie foods had gone up by an average of 19.5%.

Drewnowski doesn't have any later figures, but he speculates that "those trends are probably worse now."

Shopping patterns

Researchers have studied consumers' behavior in situations where the prices of high-calorie foods stay constant but the prices of low-calorie foods go up (and vice versa).

For example, a team from the State University of New York at Buffalo studied the grocery shopping patterns of 47 mothers ages 25 to 50 in a laboratory set up to simulate a grocery store. The mothers chose their "purchases" from cards representing 60 different foods -- half considered healthful and low-calorie, and half unhealthful and high-calorie -- with pictures on the front and nutritional information on the back. "Prices" of the foods were displayed too, and varied in different segments of the study.

When prices were raised, the study found, moms bought less of both the low- and high-calorie foods. That's consistent with the idea that rising prices these days could lead people to buy less food.

If that were to happen, it could have some very negative consequences, of course, including hunger and malnutrition. On the plus side, it might help to ease the nation's obesity problem.

That's a nice thought. But for it to actually happen, overweight people would need to cut back on eating high-calorie food -- and that is not what the study found.

"Leaner, perhaps more health-conscious mothers," the authors wrote, were sensitive to price increases for high-calorie foods -- they bought fewer of them when their prices went up and sometimes even switched to foods lower in calories whose prices had not increased.